How do I publish pages which aren’t in the repository like that?
Thanks for being here! At first glace, it appears the owner of that repo has this demo page’s code on a private repository.
GitHub Pages sites can only be served from private repositories on the Pro plan. GitHub Pages sites are still free on the Free plan for sites hosted from public repositories.
You can compare all the features for the various plans here:
I hope this helps!
Thank you for explaining! I see.